@phdthesis{Fuerstenau2008, author = {F{\"u}rstenau, Cornelia}, title = {The impact of silvicultural strategies and climate change on carbon sequestration and other forest ecosystem functions}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-27657}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {Forests are a key resource serving a multitude of functions such as providing income to forest owners, supplying industries with timber, protecting water resources, and maintaining biodiversity. Recently much attention has been given to the role of forests in the global carbon cycle and their management for increased carbon sequestration as a possible mitigation option against climate change. Furthermore, the use of harvested wood can contribute to the reduction of atmospheric carbon through (i) carbon sequestration in wood products, (ii) the substitution of non-wood products with wood products, and (iii) through the use of wood as a biofuel to replace fossil fuels. Forest resource managers are challenged by the task to balance these multiple while simultaneously meeting economic requirements and taking into consideration the demands of stakeholder groups. Additionally, risks and uncertainties with regard to uncontrollable external variables such as climate have to be considered in the decision making process. In this study a scientific stakeholder dialogue with forest-related stakeholder groups in the Federal State of Brandenburg was accomplished. The main results of this dialogue were the definition of major forest functions (carbon sequestration, groundwater recharge, biodiversity, and timber production) and priority setting among them by the stakeholders using the pair-wise comparison technique. The impact of different forest management strategies and climate change scenarios on the main functions of forest ecosystems were evaluated at the Kleinsee management unit in south-east Brandenburg. Forest management strategies were simulated over 100 years using the forest growth model 4C and a wood product model (WPM). A current climate scenario and two climate change scenarios based on global circulation models (GCMs) HadCM2 and ECHAM4 were applied. The climate change scenario positively influenced stand productivity, carbon sequestration, and income. The impact on the other forest functions was small. Furthermore, the overall utility of forest management strategies were compared under the priority settings of stakeholders by a multi-criteria analysis (MCA) method. Significant differences in priority setting and the choice of an adequate management strategy were found for the environmentalists on one side and the more economy-oriented forest managers of public and private owned forests on the other side. From an ecological perspective, a conservation strategy would be preferable under all climate scenarios, but the business as usual management would also fit the expectations under the current climate. In contrast, a forest manager in public-owned forests or a private forest owner would prefer a management strategy with an intermediate thinning intensity and a high share of pine stands to enhance income from timber production while maintaining the other forest functions. The analysis served as an example for the combined application of simulation tools and a MCA method for the evaluation of management strategies under multi-purpose and multi-user settings with changing climatic conditions. Another focus was set on quantifying the overall effect of forest management on carbon sequestration in the forest sector and the wood industry sector plus substitution effects. To achieve this objective, the carbon emission reduction potential of material and energy substitution (Smat and Sen) was estimated based on a literature review. On average, for each tonne of dry wood used in a wood product substituting a non-wood product, 0.71 fewer tonnes of fossil carbon are emitted into to the atmosphere. Based on Smat and Sen, the calculation of the carbon emission reduction through substitution was implemented in the WPM. Carbon sequestration and substitution effects of management strategies were simulated at three local scales using the WPM and the forest growth models 4C (management unit level) or EFISCEN (federal state of Brandenburg and Germany). An investigation was conducted on the influence of uncertainties in the initialisation of the WPM, Smat, and basic conditions of the wood product sector on carbon sequestration. Results showed that carbon sequestration in the wood industry sector plus substitution effects exceeded sequestration in the forest sector. In contrast to the carbon pools in the forest sector, which acted as sink or source, the substitution effects continually reduced carbon emission as long as forests are managed and timber is harvested. The main climate protection function was investigated for energy substitution which accounted for about half of the total carbon sequestration, followed by carbon storage in landfills. In Germany, the absolute annual carbon sequestration in the forest and wood industry sector plus substitution effects was 19.9 Mt C. Over 50 years the wood industry sector contributed 70\% of the total carbon sequestration plus substitution effects.}, language = {en} } @article{LandholmPradhanWegmannetal.2019, author = {Landholm, David M. and Pradhan, Prajal and Wegmann, Peter and Romero Sanchez, Miguel Antonio and Suarez Salazar, Juan Carlos and Kropp, J{\"u}rgen}, title = {Reducing deforestation and improving livestock productivity: greenhouse gas mitigation potential of silvopastoral systems in Caqueta}, series = {Environmental research letters}, volume = {14}, journal = {Environmental research letters}, number = {11}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1748-9326}, doi = {10.1088/1748-9326/ab3db6}, pages = {12}, year = {2019}, abstract = {Colombia's agriculture, forestry and other land use sector accounts for nearly half of its total greenhouse gas (GHG) emissions. The importance of smallholder deforestation is comparatively high in relation to its regional counterparts, and livestock agriculture represents the largest driver of primary forest depletion. Silvopastoral systems (SPSs) are presented as agroecological solutions that synergistically enhance livestock productivity, improve local farmers' livelihoods and hold the potential to reduce pressure on forest conversion. The department of Caquet{\´a} represents Colombia's most important deforestation hotspot. Targeting smallholder livestock farms through survey data, in this work we investigate the GHG mitigation potential of implementing SPSs for smallholder farms in this region. Specifically, we assess whether the carbon sequestration taking place in the soil and biomass of SPSs is sufficient to offset the per-hectare increase in livestock GHG emissions resulting from higher stocking rates. To address these questions we use data on livestock population characteristics and historic land cover changes reported from a survey covering 158 farms and model the carbon sequestration occurring in three different scenarios of progressively-increased SPS complexity using the CO2 fix model. We find that, even with moderate tree planting densities, the implementation of SPSs can reduce GHG emissions by 2.6 Mg CO2e ha-1 yr-1 in relation to current practices, while increasing agriculture productivity and contributing to the restoration of severely degraded landscapes.}, language = {en} } @article{MilcuHeimEllisetal.2011, author = {Milcu, Alexandru and Heim, Angela and Ellis, Richard J. and Scheu, Stefan and Manning, Pete}, title = {Identification of general patterns of nutrient and labile carbon control on soil carbon dynamics across a successional gradient}, series = {Ecosystems}, volume = {14}, journal = {Ecosystems}, number = {5}, publisher = {Springer}, address = {New York}, issn = {1432-9840}, doi = {10.1007/s10021-011-9440-z}, pages = {710 -- 719}, year = {2011}, abstract = {Carbon (C) inputs and nutrient availability are known to affect soil organic carbon (SOC) stocks. However, general rules regarding the operation of these factors across a range of soil nutrient availabilities and substrate qualities are unidentified. "Priming" (stimulated decomposition by labile C inputs) and 'preferential substrate utilization' (retarded decomposition due to shifts in community composition towards microbes that do not mineralize SOC) are two hypotheses to explain effects of labile C additions on SOC dynamics. For effects of nutrient additions (nitrogen and phosphorus) on SOC dynamics, the stoichiometric (faster decomposition of materials of low carbon-to-nutrient ratios) and 'microbial mining' (that is, reduced breakdown of recalcitrant C forms for nutrients under fertile conditions) hypotheses have been proposed. Using the natural gradient of soil nutrient availability and substrate quality of a chronosequence, combined with labile C and nutrient amendments, we explored the support for these contrasting hypotheses. Additions of labile C, nitrogen (N), phosphorus (P), and combinations of C and N and C and P were applied to three sites: 2-year fallow grassland, mature grassland and forest, and the effects of site and nutrient additions on litter decomposition and soil C dynamics were assessed. The response to C addition supported the preferential substrate hypothesis for easily degradable litter C and the priming hypothesis for SOC, but only in nitrogen-enriched soils of the forest site. Responses to N addition supported the microbial mining hypothesis irrespective of C substrate (litter or SOC), but only in the forest site. Further, P addition effects on SOC support the stoichiometric hypothesis; P availability appeared key to soil C release (priming) in the forest site if labile C and N is available. These results clearly link previously contrasting hypotheses of the factors controlling SOC with the natural gradient in litter quality and nutrient availability that exists in ecosystems at different successional stages. A holistic theory that incorporates this variability of responses, due to different mechanisms, depending on nutrient availability and substrate quality is essential for devising management strategies to safeguard soil C stocks.}, language = {en} } @article{PuppeLeueSommeretal.2022, author = {Puppe, Daniel and Leue, Martin and Sommer, Michael and Schaller, J{\"o}rg and Kaczorek, Danuta}, title = {Auto-fluorescence in phytoliths}, series = {Frontiers in Environmental Science}, volume = {10}, journal = {Frontiers in Environmental Science}, publisher = {Frontiers Media}, address = {Lausanne}, issn = {2296-665X}, doi = {10.3389/fenvs.2022.915947}, pages = {14}, year = {2022}, abstract = {The detection of auto-fluorescence in phytogenic, hydrated amorphous silica depositions (phytoliths) has been found to be a promising approach to verify if phytoliths were burnt or not, especially in archaeological contexts. However, it is unknown so far at what temperature and how auto-fluorescence is induced in phytoliths. We used fluorescence microscopy, scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), and Fourier transform infrared spectroscopy to analyze auto-fluorescence in modern phytoliths extracted from plant samples or in intact leaves of winter wheat. Leaves and extracted phytoliths were heated at different temperatures up to 600 degrees C. The aims of our experiments were i) to find out what temperature is needed to induce auto-fluorescence in phytoliths, ii) to detect temperature-dependent changes in the molecular structure of phytoliths related to auto-fluorescence, and iii) to derive a mechanistic understanding of auto-fluorescence in phytoliths. We found organic compounds associated with phytoliths to cause auto-fluorescence in phytoliths treated at temperatures below approx. 400 degrees C. In phytoliths treated at higher temperatures, i.e., 450 and 600 degrees C, phytolith auto-fluorescence was mainly caused by molecular changes of phytolith silica. Based on our results we propose that auto-fluorescence in phytoliths is caused by clusterization-triggered emissions, which are caused by overlapping electron clouds forming non-conventional chromophores. In phytoliths heated at temperatures above about 400 degrees C dihydroxylation and the formation of siloxanes result in oxygen clusters that serve as non-conventional chromophores in fluorescence events. Furthermore, SEM-EDX analyses revealed that extractable phytoliths were dominated by lumen phytoliths (62\%) compared to cell wall phytoliths (38\%). Our findings might be not only relevant in archaeological phytolith-based examinations, but also for studies on the temperature-dependent release of silicon from phytoliths and the potential of long-term carbon sequestration in phytoliths.}, language = {en} } @phdthesis{Rock2008, author = {Rock, Joachim}, title = {Klimaschutz und Kohlenstoff in Holz : Vergleich verschiedener Strategien}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17531}, school = {Universit{\"a}t Potsdam}, year = {2008}, abstract = {W{\"a}lder haben im Bezug zum Klimawandel mehrere Rollen: Sie sind Kohlenstoffspeicher, -senken, sowie Lieferanten von Holz als Rohstoff f{\"u}r die Kohlenstoffspeicher in Produkten und f{\"u}r Substitution fossiler Energietr{\"a}ger. Unter Klimaschutzgesichtspunkten ist es w{\"u}nschenswert, die Kohlenstoffbindung im Gesamtsystem aus Senken, Speichern und Substitution zu maximieren und zu entscheiden, welche Maßnahme an welchem Ort und unter welchen Rahmenbedingungen den gr{\"o}ßten positiven Effekt auf die CO2-Bilanz hat. Um die Speicherung in den verschiedenen Kompartimenten erfassen zu k{\"o}nnen m{\"u}ssen geeignete Inventurverfahren zur Verf{\"u}gung stehen. Die IPCC - GPG benennen die Speicher und geben zum Teil Anforderungen an die zu erreichende Inventurgenauigkeit. Aus der klassischen Forsteinrichtung stehen gen{\"u}gend Methoden zur Verf{\"u}gung, um das oberirdische Volumen sehr genau zu erheben. Um den Anforderungen an ein umfassendes Kohlenstoffmonitoring gen{\"u}gen zu k{\"o}nnen, m{\"u}ssen diese Verfahren in den Bereichen Erfassung von St{\"o}rungsfolgen, Totholzdynamik, Boden und der Berechnung von Gesamt-Kohlenstoffvorr{\"a}ten aus dem Holzvolumen erg{\"a}nzt werden. Zus{\"a}tzlich bietet sich an, Bewirtschaftungsmaßnahmen entsprechend zu erfassen, um ihre Auswirkung auf die Kohlenstoffdynamik ebenfalls feststellen zu k{\"o}nnen. Dies ist f{\"u}r die Berichterstattung zwischen Inventuren sowie f{\"u}r die Herausrechnung von nicht-menschenverursachter erh{\"o}hter Kohlenstoffspeicherung („factoring out" im Sinne des KP) w{\"u}nschenswert. Wenn Bewirtschaftungsmaßnahmen unterschieden werden k{\"o}nnen und ihre Auswirkungen auf C-Vorr{\"a}te bestimmbar sind, ist eine Verifizierung erh{\"o}hter Speicherung auch z. B. f{\"u}r Projekte nach Art. 3.4 des KP durchf{\"u}hrbar. Diese Arbeiten stecken jedoch noch in der Anfangsphase. Im Rahmen dieser Arbeit wurde die erste verf{\"u}gbare qualitative {\"U}bersicht zu dieser Thematik erstellt. Die Optimierung der Wald-Holz-Option wird durch die im Kyoto-Protokoll (und den zugeh{\"o}rigen Folgeabkommen) vereinbarten Regelungen erschwert, da einerseits zwischen Wald und Produkten eine Trennung besteht und andererseits die Maßnahmenverantwortlichem im Wald nicht direkt durch das KP angesprochen werden. Eingeschlagenes Holz wird im Wald als Emission betrachtet und dem entsprechenden Sektor zugerechnet, was jedoch keine Auswirkungen auf den Forstbetrieb hat. Dieser profitiert im Gegenteil derzeit von der durch die - auch von KP Regelungen beeinflussten - Holzpreise und erh{\"o}ht die Nutzungen, was zu Vorratsabsenkungen im Wald f{\"u}hrt. Ob diese Absenkungen durch die Substitutionseffekte des geernteten Holzes kompensiert werden ist derzeit noch nicht gekl{\"a}rt. Um die Trennung zwischen Wald und Produktpool aufzuweichen bietet es sich an, die Waldbesitzer am Emissionsrechtehandel teilhaben zu lassen, damit nicht nur die Ernte sondern auch der Ernteverzicht finanziell bewertbar sind. Sozio-{\"o}konomische Szenarien zur k{\"u}nftigen Entwicklung der Landwirtschaft zeigen große Fl{\"a}chenpotentiale, die f{\"u}r die Nahrungs- und Futtermittelproduktion nicht mehr ben{\"o}tigt werden oder nicht mehr rentabel sein werden. Eine m{\"o}gliche Nutzung in Zukunft sind Energieholzplantagen. Informationen zu m{\"o}glichen Ertr{\"a}gen sind zur Zeit noch unzureichend und Analysen zur Nachhaltigkeit dieser Ertr{\"a}ge unter Klimawandel sind nicht vorhanden. In dieser Arbeit wurde mit dem {\"o}kophysiologischen Waldwachstumsmodell 4C an Beispielsstandorten in Brandenburg das Wachstum von Energieholzplantagen unter derzeitigem Klima und unter verschiedenen regionalisierten Klimawandelszenarien bis 2055 simuliert. Ertragspotentiale liegen derzeit auf der Mehrzahl der Standorte im positiven Bereich, auf einigen Standorten ist jedoch nur begrenzt mit positiven Deckungsbeitr{\"a}gen zu rechnen. Bis 2055 ist in allen Szenarien mit einem leichten R{\"u}ckgang der Ertr{\"a}ge und einer deutlicheren Verringerung der Grundwasserneubildung unter Energieholzplantagen zu rechnen. Die Unterschiede zwischen Standorten sind jedoch derzeit und unter zuk{\"u}nftig m{\"o}glichem Klima st{\"a}rker als klimabedingte {\"A}nderungen. Bei der großfl{\"a}chigen Anlage von Energieholzplantagen k{\"o}nnen negative Auswirkungen auf die Biodiversit{\"a}t und andere Naturschutzbelange eintreten. Eine diese Effekte abmildernde Fl{\"a}chengestaltung, die trotzdem Ertr{\"a}ge auf dem Niveau heutiger Vollerwerbslandwirtschaft erreicht, ist m{\"o}glich. Insgesamt l{\"a}sst sich f{\"u}r die Optimierung der Wald-Holz-Option feststellen, dass eine Nicht-Nutzung bestehender Waldfl{\"a}chen unter Klimaschutzgesichtspunkten negativ ist. Der Substitutionseffekt geernteten Holzes betr{\"a}gt zus{\"a}tzliche ca. 70 Prozent Kohlenstoff, die in dieser Form in nicht bewirtschafteten mitteleurop{\"a}ischen W{\"a}ldern nicht zus{\"a}tzlich gespeichert werden. Es ist davon auszugehen, dass sich durch die Ber{\"u}cksichtigung von Substitutionseffekten andere - wahrscheinlich k{\"u}rzere - als die heute {\"u}blichen Produktionszeiten ergeben. Auf bisher waldfreien Fl{\"a}chen ist die Anlage von Energieholzplantagen positiver zu werten als eine normale Aufforstung.}, language = {de} } @article{SandhageHofmannLinstaedterKindermannetal.2021, author = {Sandhage-Hofmann, Alexandra and Linst{\"a}dter, Anja and Kindermann, Liana and Angombe, Simon and Amelung, Wulf}, title = {Conservation with elevated elephant densities sequesters carbon in soils despite losses of woody biomass}, series = {Global change biology}, volume = {27}, journal = {Global change biology}, number = {19}, publisher = {Blackwell Science}, address = {Oxford [u.a.]}, issn = {1354-1013}, doi = {10.1111/gcb.15779}, pages = {4601 -- 4614}, year = {2021}, abstract = {Nature conservation and restoration in terrestrial ecosystems is often focused on increasing the numbers of megafauna, expecting them to have positive impacts on ecological self-regulation processes and biodiversity. In sub-Saharan Africa, conservation efforts also aspire to protect and enhance biodiversity with particular focus on elephants. However, elephant browsing carries the risk of woody biomass losses. In this context, little is known about how increasing elephant numbers affects carbon stocks in soils, including the subsoils. We hypothesized that (1) increasing numbers of elephants reduce tree biomass, and thus the amount of C stored therein, resulting (2) in a loss of soil organic carbon (SOC). If true, a negative carbon footprint could limit the sustainability of elephant conservation from a global carbon perspective. To test these hypotheses, we selected plots of low, medium, and high elephant densities in two national parks and adjacent conservancies in the Namibian component of the Kavango Zambezi Transfrontier Area (KAZA), and quantified carbon storage in both woody vegetation and soils (1 m). Analyses were supplemented by the assessment of soil carbon isotopic composition. We found that increasing elephant densities resulted in a loss of tree carbon storage by 6.4 t ha(-1). However, and in contrast to our second hypothesis, SOC stocks increased by 4.7 t ha(-1) with increasing elephant densities. These higher SOC stocks were mainly found in the topsoil (0-30 cm) and were largely due to the formation of SOC from woody biomass. A second carbon input source into the soils was megaherbivore dung, which contributed with 0.02-0.323 t C ha(-1) year(-1) to ecosystem carbon storage in the low and high elephant density plots, respectively. Consequently, increasing elephant density does not necessarily lead to a negative C footprint, as soil carbon sequestration and transient C storage in dung almost compensate for losses in tree biomass.}, language = {en} }